1. Field of the Invention
The present invention generally relates to the art of microelectronic integrated circuits, and more specifically to a single chip processor architecture utilizing volatile memory for program memory in addition to a communications interface.
2. Description of the Related Art
Existing microprocessor systems store programs using a combination of volatile memory, including random access memory (RAM), and non-volatile memory, including read only memory (ROM), EPROM, and flash RAM. Non-volatile memory provides integrity for stored programs and lower costs per bit of space. However, non-volatile programs are generally fixed and cannot be reprogrammed or replaced without completely swapping out the non-volatile memory components. Each non-volatile program tends to be application specific, and the need for new or updated programs increases the costs associated with manufacturing and maintaining up to date inventory.
Non-volatile memory is also frequently slower than RAM, negatively impacting system performance. Programs stored in non-volatile memory must frequently be loaded into RAM for execution.
A diagram of a typical system 10 is presented in FIG. 1. The ROM 11 contains information, such as a program or programs, which the processor 12 determines should be accessed and executed. Processor 12 issues a request to ROM 11 which loads the program into RAM 13. The program may pass through processor 12 at this stage. Once the program is loaded into RAM, the system begins executing program steps. This process tends to be very slow, and as noted the ROM 11 has particular disadvantages for implementation and use on a single chip arrangement.
Production of non-volatile memory hardware elements such as ROM may require manufacturing processes which are inefficient for constructing a microprocessor. The result is that manufacturing a microprocessor based system on a single chip tends to be difficult when non-volatile memory is required.
The need therefore exists for a simple and efficient way to provide programs to RAM without the expensive and time consuming requirements associated with non-volatile memory. Such a system should provide the capability for fabrication on a single chip.
It is therefore an object of the current invention to provide a system for minimizing the need for non-volatile memory, or potentially eliminating the need for non-volatile memory altogether.
It is another object of the current invention to provide a simple and relatively inexpensive system for providing updated information or programs to volatile memory.
It is yet another object of the current invention to provide the components of the system on a single chip which may be manufactured inexpensively and simply.